This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2003-57173 filed in Korea on Aug. 19, 2003, which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to a color optical link using a transparently jacketed plastic optical fiber, which optically transmits data and uses light, scattered and emitted to the outside, as decorative illumination, and a method for achieving the color optical link.
2. Description of Related Art
As well known to those skilled in the art, communications used in homes are divided into wire communications and wireless communications. The wire communications are developed from a type using conventional copper wires to a type using glass optical fibers and/or POFs (Plastic Optical Fibers) serving as FITHs (Fibers In The Home).
One strand of the copper wires serves as one communication line. A cable using a plurality of strands of the copper wires for achieving several communication lines is thicker and possess a large weight. Furthermore, copper wire has a maximum transmission capacity of 500 Mbps, which is insufficient to meet the trend of multimedia requiring broadband data transmission.
In order to solve the above drawbacks, optical fibers have been proposed. The optical fibers independently transmit light having different wavelengths via a single communication line without the interference of signals between the respective wavelengths, thus advantageously simplifying the communication line. Since graded index types of the glass and plastic optical fibers have a data transmission capability of more than 1 Gbps, the graded index-type glass and plastic optical fibers play a leading role in the multimedia trend.
A glass optical fiber is a very thin glass fiber, which has poor bending properties. Accordingly, when the glass optical fiber is broken in a jacket, the broken glass optical fiber penetrates the jacket and is exposed to the outside, thus being very dangerous. Particularly, when the glass optical fiber is broken in use, it must be repaired using expensive equipment. Since the glass optical fiber, which is used in long-distance communication, functions to transmit data over a comparatively long distance, it transmits a signal having an infrared ray wavelength band with low optical loss, thus allowing the transmission of light to be invisible to the naked eye. Since one strand of the glass optical fiber for transmitting a single wavelength has a low price, there has been proposed a product of glass optical fibers comprising only one strand for transmitting one set of data. A product of glass optical fibers for transmitting data having multiple wavelengths has a high price, and thus it is an unrealistic product for use in homes, while being suitable for use as fibers in the home.
Plastic optical fibers have high optical loss when compared to glass optical fibers, and thus are incapable of being used in long-distance communication but are suitable for short-distance communication use in homes. Further, plastic optical fibers have good bending properties and is thus are not easily broken. However, when plastic optical fibers are broken, the broken parts can be easily reconnected. Plastic optical fibers transmit a signal having a visible light wavelength band with an optical loss 100 times as large as that of glass optical fibers, thus allowing a comparatively large amount of light to be emitted, in transmission, to the outside by scattering, which becomes visible to the naked eye. Most optical links, which are installed in homes, have a narrow bandwidth of approximately 50 Mbps. Accordingly, even when R (red), G (green), B (blue) and Y (yellow) lights are simultaneously transmitted using low-priced LED light sources, the total cost for installing the necessary LED light sources is inexpensive. Of course, glass optical fiber fibers can use LEDs. However, since it is difficult to achieve optical coupling between glass optical fibers with a core having a diameter of 50 μm and LED light sources having a diameter of 300 μm, glass optical fibers having a low capacitance must employ expensive coupling components in order to achieve the optical coupling therebetween. On the other hand, plastic optical fibers having a core with a large diameter is easily coupled with the LED light sources, thus allowing a large amount of light emitted from the light sources to be introduced thereinto for transmission.
The glass optical fiber is mainly used outdoors, thus generally including an opaque jacket for protecting the glass optical fiber from the external environment. On the other hand, the plastic optical fiber used in homes may include a transparent jacket for allowing a part of the transmitted light to be emitted to the outside and then used for the purpose of illumination.
Fraunhofer in Germany discloses a MUX/DEMUX (multiplexer/demultiplexer) using a plastic optical fiber for transmitting light having multiple wavelengths. Here, an optical link is achieved by inputting R, G and B LED signals, arranged in series, into an optical fiber. Since the R, G and B LED signals are arranged in series, this conventional optical link is disadvantageous in that it has an increased volume and the intensity of emitted light must be differently varied so as to compensate for light passing through a reflecting mirror.